Why is it that people will spend hours on the exterior of the boat
and then you will see a bilge area that could gag a horse. I wonder if people are afraid
of what's down there or if they feel that if you just leave the hatches closed nobody will
The entire health of a boat is mirrored by the health of the bilge area. We
are not talking spotless here, we are just pointing out basic safety and health
So what's the cause? Leaking engine fluids, sanitation system leaks, rain
water, spilled food, refrigerator drains, bath/shower discharge, leaking sea water,
condensation, and mold/mildew are the contributing factors and they all seem to find their
way to the bilge.
Since it hard to stop this in-flow to the bilge, it should be reduced and
managed. The issue of mold and sanitation is our first concern.
Mold forms as a living feeding creature. It needs a food source for growth and cool damp
dark areas are it's favorite lodging. The best way to reduce mold and mildew is by
venting the bilge area as best as possible and keeping the bilge area clean. There are
also products like "Mildew Gas" which act like big moth balls to counteract
growth. By the way, sunlight is the natural enemy to mold/mildew, so let the sun shine
Constant air movement is the best agent to
fight mold. Whether you install a power vent, de-humidifier, or heat stick, make sure
it operates on a regular basis. Pricing of "Solar-electric vents" is becoming relatively
reasonable. You should shop around and install at least one in the cabin top of your boat
to encourage air movement.
Since moisture is the catalyst, it is well worth getting down to solving those annoying
One system often over looked is the shower sump. Most shower sumps serve the
shower and the floor of the head area. Even if you don't use the shower, periodic wash
down of the head area means this system should be working properly. Some shower sumps
aren't sealed with a lid to prevent a potential overflow. It wouldn't be a bad idea to try
to fit a lid. If that isn't possible you need to periodically test that the discharge pump
and auto-switch are functioning.
Air-Conditioning, refrigerator, and icemaker condensate lines are a bit tough to resolve
but, if they can be run to the shower sump or over the side (thru-hull)
you'll find you won't have as much dampness in the cabin area and under your decks in the
Besides being against the law, engine oil leaks and spills need to be reduced
and controlled. Actually, it's not against the law to have an oil leak but it is against
the law to pump bilge water that contains oil, over the side into the water. It is the
boat owners obligation to prevent oil discharge of any sort and amount. The best way to
reduce unwanted oil emissions into the bilge is to maintain your flame arrestor, replace
any PCV valve on the motor, and to use extreme care when changing your oil and filter.
Sounds too easy? Those are the biggest causes of oil in the bilge. The next cause is oil
leaks due to mechanical failures, which we cover in another section.
If you've been inspected by the Coast Guard Auxiliary, lately, you know that
they will look for an oil absorption sock and/or pad under each motor and/or the lowest
part of the boat. Although they may not be black with oil and dirt, it is still a good
idea to replace wet or water-logged ones every couple of months.
Green anti-freeze is toxic and every attempt needs to be made to prevent it's
discharge. Besides loss during anti-freeze changes, the one biggest cause of pollution by
Green anti-freeze is people who use it to winterize their engines. It is against the law,
Don't do it.
Sanitation leaks aren't always because of the system itself. Sailboaters often have
sanitation leaks because of the nature of using the facilities while under way. This
spillage then is often washed into the bilge area, thru the floor drain of the head area.
Why sail boat builders don't put shower sumps into sail boats, I'll never know... Anyway,
sanitation leaks are easy to find. It's rarely a fun job but the dividends are
If your sanitation system is older than 10 to 15 years old, you probably need
to look closely at the end fittings and the hose itself. The older plastic end
fittings have a tendency to become brittle and crack. The hose doesn't necessarily start
to leak a much as it starts to smell from absorption. If you note discoloration or
crystals forming near the fittings, it's definitely time to start replacing with new.
Commercial bilge cleaners.
There has been a bit written lately about bilge cleaners and their affect on
the environment. Even though it may say "Biodegradable" on the bottle, the
concern is more about what the cleaner is dissolving during the cleaning process. It is
this solution that is pumped over the side that have people concerned. If your just doing
a quick freshening of the bilge to reduce mold buildup once a year, there shouldn't be
much of a problem. But if your constantly doing it to clean away the evidence of oil and
sanitation leaks, you need to look at fixing those leaks.
Clorox bleach as a bilge sanitation device.
Although not recommended for sanitation systems because of the damage it
could do to hoses and fittings, a 10 to 1 mix of Clorox Bleach or equivalent, put
into the bilge water on a weekly basis can be effective in reducing mold. Usually within
24 to 48 hours, the bleach slowly evaporates and acts similar to the mildew gas
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